THIS FEATURE IS AVAILABLE VIA latest fixes, and will be part of 1.9.5
At time of this writting (@20121117) ONLY FOR Mantis SOAP and Bugzilla XML-RPC, IF YOU HAVE ISSUE TRACKING INTEGRATION Configured (in the right way. see other posts on forum that explain how to do this) you will find TWO BUTTONS when executing a TEST CASE:
1. (the old one) that allow you to ADD on TestLink AN EXISTENT ISSUE/BUG ID.
2. NEW! will create WITHOUT ASKING YOU NOTHING a new Issue/Bug and will do the link on TL.
some technical details of Create Bug with JUST ONE CLICK
Right now you need to create a user to access OUR MANTIS SITE to access the tickets:
http://mantis.testlink.org/view.php?id=5350
http://mantis.testlink.org/view.php?id=5349
http://mantis.testlink.org/view.php?id=5347
we are going to create simple documentation in future (help is ALWAYS welcomed) and as usual consider to donate to help us keep improving TestLink.